text:
What is the loud noise of a helicopter when the rotors are not yet moving?
What is the loud noise when a helicopter is ready to start flying, but the rotor is not yet rotating?
For example at Trump's "chopper talk", when he is intercepted by reporters on the way to Marine One? The helicopter nearby makes really loud noise already, which makes it hard to communicate between reporters an Trump - so it seems to be something important. It's not the rotor itself, as it's not rotating.

The sound you're hearing is the APU (Auxiliary Power Unit) running.
Turbine (jet) engines turn at a much higher RPM than reciprocating engines. This means that an electric starter motor would have to be bigger and heavier in order to produce enough torque to get the engine moving fast enough. The bigger the engine, the bigger the starter (and the batteries to drive it). At some point, it becomes impractical to have an electric starter on a big turbine engine.
That's where an APU comes in. It's essentially a small jet engine. Small enough, in fact, to be started electrically. Once it's running, it feeds high-pressure air to spin the main engine fast enough for it to start. It can also provide electricity, run the A/C, etc.

It could also be the main engines idling with the rotor brake set, but watching the vids I agree it sounds more like an APU running.

It's mainly the starter batteries that would be way too heavy. See the 787, which uses electric starters (even though the Trent certainly is "big"), but still needs an APU to feed them.

“Turbine (jet) engines turn at a much higher RPM than reciprocating engines” – that would seem to be quite irrelevant here, since it is actually easier to build high-RPM electric motors than low-RPM ones of the same power, especially at small size&mass. As TooTea says, the problem isn't in electric motors but electric power supply – which raises the question why helicopters aren't just started with an electric motor supplied by an umbilical cord, to avoid wear and fuel demand of an APU.

@leftaroundabout Probably because there are a lot more places to land a helicopter that won't have any ground support than there are to land airplanes.

@leftaroundabout, if ground power is available, it might be used, but I doubt it is available on the White House lawn. Start carts are a hassle of their own.

@T.J.L., even large fixed-wing aircraft often use APU because ground power is either too much hassle, not available or not sufficient. There is a comment by Terry (retired 747 pilot) somewhere around how it was problem to scramble a start cart capable of starting a 747 somewhere in Harare—they simply didn't have a large enough one at all, so two had to be hooked, which the 747 fortunately supports. I've also read mention by an ATR-42 pilot how in some places in India they simply were not used to bring the power cart around (ATR-42 has no APU and has to use the engine with propeller brake).

@JanHudec Sure... My only point was "places a helicopter can land that definitely won't have ground support" is a far larger set than "places a fixed-wing aircraft can land that definitely won't have ground support". One could argue that the entire purpose of helicopters is to go those very places.

You may be expecting the rotor to spin up in lock-sync with the engine.
That's not quite what happens on a turbine helicopter.
Turbine helicopter engines (turboshaft engines) have a turbojet engine inside them that makes thrust.  This engine has a shaft of its own - so that its compressor blades are connected to its own turbine blades. The turbojet's thrust acts on a second "stage" of turbine blades, which are on their own shaft.  Those connect to the helicopter rotor.
So the "internal" turbojet engine can be started and idled, without making enough thrust to spin up the second stage.   Turboprop engines work the same way, and you'll see where they are "barely turning over" at times.  That is the idle thrust working on their rather free-turning mechanism.
Some helicopters have a rotor brake so they can keep the rotor from spinning slowly like that.
Closer to home, that same effect occurs in your car's automatic transmission.  The engine is able to turn at idle speeds while in gear.  That's why you have to hold the brake constantly, the engine's "thrust" will creep the car up to about 5 mph if you don't.
Both of these are a hydraulic coupling - transmission fluid in the car, and jet engine exhaust air in the helicopter/turboprop/turbofan.
Once you advance the throttle to meaningful amounts of power, this "slip" becomes insignificant, and power is transmitted through just fine.


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Why can't sonic booms be heard at air shows?
At air shows with fighter jets I would expect there would be a demonstration of supersonic flight. But in this flight of a Eurofighter Typhoon, no sonic boom was heard.
What is the reason?
Is it that there is no supersonic flight involved due to loudness or needing a bigger distance to accelerate?
Or is the sonic boom inaudible for a reason related to the short time delay of the sound between the noise source and the microphone, or some other physical reason?

Sonic booms over populated areas were essentially forbidden in the US sometime around 1960.  Prior to that I heard several.  Have not heard one since.

I think it was the late 60s because I remember hearing some as a kid.  I thought it was cool...

I heard sonic bombs as a kid, in the San Fernando Valley part of Los Angeles.  Wonder where they were flying out of?  We also frequently heard rocket engine testing from the Rocketdyne and Rockwell facilities in the Chatsworth hills.

"I would expect there would be a demonstration of supersonic flight".  Why?  (I, on the other hand, would hope that there would be a demonstration of supersonic flight.)

I heard sonic booms on a regular basis in middle Tennessee from '05-'08.  They had to flight test the F-22 Raptors over Arnold AFB and there would be 2 sonic booms.  One was the F-22, the second was the chase plane.

OP, no supersonic flight is allowed at an airshow - it's that simple.

This question is being "over-answered" in very confusing ways.  The only thing OP wants to be told is "There is never any supersonic flight at airshows."

In a large part of the video linked in the question, you can see that the fighter has it's flaps deployed (on the leading edge of its wings). That suggests to me (though I'm not a very sophisticated observer of aviation stuff, I could be wrong) that it's at the slower-edge of its performance envelope, and at more risk of stalling than going supersonic.

@RyanMortensen I worked at Arnold one summer during that period. I hadn't previously heard a sonic boom. When I was meeting with the team I would be working with during my first week there, I remember hearing the building shake as if from a significant explosion and everyone just ignored it and kept talking. Apparently they saw the odd look on my face and said, "Oh, sonic boom," then continued talking about the project.

I'm not sure why some people are claiming supersonic flight is not allowed at an airshow, and implying this is true on our entire planet.  I've been to multiple airshows that featured supersonic flight.  They usually warn you first so you can cover your ears.  After the sonic boom, you get to listen to the alarms of most nearby vehicles being triggered.  And children crying.

@RyanMortensen That is quite interesting, as it shows a direct argument why it is avoided even from a moderate hight that would be "very loud", but acceptable for adults. It is still to loud for children, even with full to protect the child.

The only airshows I have went to are the Blue Angels, and they don't do supersonic.

In a lot of areas, sonic booms are illegal over land or near residential areas. Yes it's loud, yes it's potentially damaging, especially at low altitudes. I've been to a lot of airshows, I've never seen a supersonic demo.

this is true. In Europe, where the eurofighter is used the most super sonic flight is prohibited by the noise level limits a plane may produce. It is only alowed in acute alarm situations. I whitnessed this once in Nürnberg during an incident. You Really don´t need speakers to hear the boom. It shakes your bones from 15km away.

@Nefrin Not all European countries have the luxury of the sea to train supersonic flight. In Czechia planned training supersonic flights  are performed above 10 km.

While it's true that some countries (such as the U.S.) make it illegal for civilians to fly supersonic over land, this restriction is rarely, if ever, legally applicable to the military. Of course, they'll still not do this at low altitude under normal circumstances for obvious reasons. Even in the U.S. where supersonic flight over land is notoriously banned for civilians, the military does it pretty regularly, just at high altitudes. We used to hear sonic booms pretty frequently near the USAF base I used to work at. It was far enough away not to do damage, but it did shake the building.

@reirab, I’m not saying it doesn’t occasionally happen, but military pilots are not allowed to fly supersonic in CONUS.

@MichaelHall I mean, I know they're not allowed to just whenever they want, but there are plenty of (relatively frequent in my experience) missions where they can and do fly supersonic over the CONUS. Of course, it's not like they're doing it at 1,000 ft AGL over populated areas.

Please help us understand when and where you have seen this occur then because in all the exercises I have been involved in if there was an accidental boom the perpetrator would be shamed in the debrief.

@Michael: see https://en.wikipedia.org/wiki/MythBusters_(2009_season)#Sonic_Boom_Sound-off. Not only did Hyneman and Savage prove that sonic booms aren't likely to damage windows on the ground, they performed their experiment in the US (Yuma, AZ to be exact). Yes, there are restrictions about where aircraft can fly supersonic over the US. But a complete blanket prohibition? Nope.

I live near the US Naval Academy, they do sonic boom shows both the day of and the day before graduation.

Ok, i admit it can be waivered under special circumstances, just like other regulations.  I'm just trying to dispel the notion that military pilots are routinely exempt.

Just for a bit of flavour, I recall an article from Air Progress from the late 70s about Darryl Greenamyer setting the low altitude absolute speed record, in his "homebuilt" F-104, of Mach 1.3 (mentioned in this article) in 1977.
For the run he had to cross very low over timing trigger devices at the start and end of the speed course at the dry lake bed at Edwards, which were set up with cars parked beside them.
I remember the description of the event by the writer who witnessed it from somewhere along the middle of the course, a safe distance away with other observers.  The F-104 passed over the car at the 1st speed trap at 60 ft AGL and passed the writer in absolute silence, and it wasn't until a second or so had passed that a sound like a dynamite explosion a couple hundred feet away went off.  All the glass of the cars at the speed traps blew out and their trunks popped open.  The writer was warned in no uncertain terms that if he didn't protect his ears he'd get hearing damage, and not to be fooled by the initially silent passage of the jet itself into taking his fingers out of his ears.
Imagine that happening at an airshow.

Sound travels at ~1100ft/s. If it was 60ft away, it wouldn't take a couple of seconds. It should basically be instant.

The boom occurs at the point at which the plane goes supersonic tho, so unless the plane went supersonic as it passed the reporter, they would see a delay. I think they're saying the plane was 60ft away, not that it went supersonic  60ft away. As long as the plane is accelerating, the distance between the plane passing, and the boom passing would be increasing.

The aircraft was supersonic before it entered the speed traps and was at 60 ft agl over the speed traps where a car was parked at each end. The reporter wasn't right under the flight path but somewhere around the mid point of the run, perhaps 1-2000 feet from the flight path where various people had assembled to watch. So the shock wave was already trailing the aircraft going into the speed run. If they were 1500 ft away, it would take over a second to reach that far at 1122 fps with a bit extra because the wave is trailing somewhat.  I've added some clarification to my post.

@djsmiley2k-CoW “the boom occurs at the point at which the plane goes supersonic”. This is not correct at all. The “boom” is the wave front of the sound generated by the jet. It is actually a constant roar. The only difference is that the wave front is compressed so that by the time it passes over you that roar happens at a single instance. It travels behind the jet and dissipates outwards at the speed of sound. It is not a single event. It is a continuous sound that you only get to hear a short snippet of.

This answer is just an anecdote.  It's completely confusing.  The OP is asking a very basic question "Is There Supersonic Flight At Airshows?" The four paras here completely fail to simply answer the question!  JK, perhaps add one introductory sentence stating the answer, then your anecdote. There's a common problem on these sites where leading experts in a field simply fail to answer very very simple questions, because to the experts it's totally obvious.

I agree that while it is a nice anecdote, it doesn't answer the question. Regarding simple answers to simple questions, I have tried that and been chastised with a canned "we expect long answers" comment.

@Fattie That is true, but the anecdote is so interesting that it's worth an answer anyway. I was aware that if it's loud, it is really loud. But that's more than just loud by an order of magnitude or two. I did not expect that, I did not do the math, and if I had, it would not give me an intuition. The answer is implicit, but the implication gives information that other answers can not convey.

As I said folks, "just for a bit of flavour"...Ron already provided the answer. I read that article 40 years ago and it's always stuck with me.

The "loud" from a sonic boom is not something that is generated from an audio device, but it is pure mechanical pressure released in a very short time frame.  You're basically doing something equivalent of dropping rocks on your eardrums directly. Most people don't understand the kind of damage this can cause because they simply have no concept of it.

It's impressive to experience it up close.  The US Navy regularly performs airpower demonstrations at sea and I have been on the flight deck for several low altitude supersonic flybys.  It is a substantial thump you feel in your whole body when it hits.

Sonic booms have a lot of, lot of, lot of throw.  There would be no way to confine a sonic boom to just the airfield. People two towns over would have have car alarms set off and houses shaken.  It would upset animals, it would upset people!  It would trigger PTSD for some and panics for others.  It would generate hundreds of phone calls to 911.
Keep in mind the airplane has to accelerate to and through supersonic well before the airfield, and then has to slow down again. It's covering a mile every 5 seconds, so this, combined with the throw, sweeps a whole lot of area.

Does that mean that it's illegal to have an aircraft with a higher landing speed than 250KIAS? I know some extreme aircraft (e.g. the Shuttle) land at very high speeds.

@Skyler Military does not need to foloow civilian rules. One is GAT, one is OAT.

@Skyler Even civilians can get the 250 below 10,000 speed restriction waived by ATC. It's mostly just there to make traffic deconfliction easier. If ATC has other ways to guarantee no traffic conflicts (and, for the Space Shuttle, they definitely did,) then there's no problem with waiving the speed restriction.

@Vladimir, The military definitely does need to follow civilian FAA rules.  Some aircraft have waivers for speed, and of course 250 can be exceeded in special use airspace, but otherwise most of the same rules apply.

They don't need to follow civilian system, they just do as a matter of policy, because of Hughes 706.

@Harper, please declare your credentials for making such a claim.  I flew in the military for 20 years and I don’t think you know what you are talking about.

@Michael I would imagine this question https://aviation.stackexchange.com/questions/12401/how-much-jurisdiction-does-the-faa-have-over-military-aircraft

It is a big leap from a detailed explanation of waivers, special use airspace, etc. to an unqualified statement that military pilots don't have to comply with FAA regulations.  Roughly 75% of our flying was IFR in the national airspace system.  You'd better believe we were required to follow the rules, flight violations are a career killer!  Speak with authority on computer programming if that is your specialty, but don't condense someone else's answer into an authoritative sounding summary unless you are able to provide some context for clarity.

@MichaelHall It sounds like I've pushed a hot button for you. You seem to be swerving out of your way to misinterpret what I said.  I am claiming you, as a line pilot, must - must - follow ATC, because of orders to that effect.   I'm saying those orders flow from high up on your chain of command, i.e. Pentagon. Any problem with that so far?

You said "they don't need to follow civilian system, they just do as a matter of policy".  While the Pentagon is certainly not within the jurisdiction of the FAA, the fact that the military requires their pilots to follow all applicable FAA regulations renders your point completely moot.  You and others make it sound like we have a choice in the matter, and could fly supersonic without consequences if we wanted.  So yes, I have a problem with that so far.

@MichaelHall I never said it's at the discretion of individual pilots. If others did, take it up with them. I am not them. My "they" pronoun referred to your statement "the military", and in my thinking, military is plural because you have to enumerate "Army Navy Air Force Marines" otherwise you're including Coast Guard.

When I say "policy" I mean the policies set as a result of the agreement between the armed serviceS and FAA that they would follow ATC (mostly). https://news.google.com/newspapers?id=y3YlAAAAIBAJ&sjid=1fIFAAAAIBAJ&pg=1008,835673&hl=en  As a result of the agreement, Congress did not mandate it with legislation.  in actual implementation, it is at the services' discretion, but they have to make a good showing of it if they don't want Congress to intervene.

Please describe what you mean by "mostly", specifically in the context of an individual military pilot's understanding of a requirement to follow FAA regulations regarding a prohibition against supersonic flight, and any consequences, (or lack thereof) for failing to comply.

"mostly" means you follow orders, or stand at account for not doing so. The benefit of an agreement instead of legislation is that this gives top Pentagon brass a range of discretion to a) initially implement the agreement in a sensible manner that allows planning, and b) deviate from the agreement where exigencies require.  This is why it's good that it's an agreement and not legislation.  All of this is "above the pay grade" of a line pilot.

Fair enough, I respect your apparent knowledge on the subject.   I have heard that the brass generally won't defend a pilot against an FAA flight deviation though, so you are correct in that the net effect is transparent to a line pilot.

John K has already provided an example of what a sonic boom feels like from very close, and Harper - Reinstate Monica describes it in general terms. Let me give you a practical example of what a sonic boom did in a radius of 100 km.
On 22 March 2018, Air France flight AF671A from Réunion to Paris Orly was flying over northern Italy when it lost radio contact with Air Traffic Control. Two Eurofighter Typhoons were sent to investigate, and as they rushed there they broke the sound barrier.
The sonic booms were heard from Aosta to Bergamo, which are 180 km apart. And at first they were mistaken for bombs. The result? Among other things, there were hundreds of calls to the police, people ran out of buildings in panic, some schools and offices were evacuated, and some windows got broken.
And at an airshow they'd fly much lower, so it would be louder!
To be fair, it was explained that the wind and weather conditions were unfortunate, as they favoured the propagation of sound, but in any case a sonic boom is way too loud to be done for fun: it's only allowed in case of emergencies.
By the way, in the end it turned out it was a false alarm, so at least there was a happy ending.
[Sources: in English, in Italian]

source: Stack Exchange

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authors: Vladimir F Героям слава

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How to file flight plan with ZZZZ?
Wikipedia mentions,

ZZZZ is a pseudo-code, used in flight plans for aerodromes with no ICAO code assigned.

How pilot actually file this flight plan? Is there anything special to do when file for ZZZZ.

Or things that aren't even aerodromes to begin with -- such as a farmer's field or a parking lot.  (Especially useful for helicopter types)

I don't know if you're asking about a specific country, but in the US it seems that you can just use it in place of a regular airport identifier and add supporting information in the remarks.
Specifically, the AIM 5-1 has several references to it, including:

(b) If no four-letter location indicator has been assigned to the
  departure aerodrome, insert ZZZZ and specify the non-ICAO location
  identifier, or fix/radial/distance from a nearby navaid, followed by
  the name of the aerodrome, in Item 18, following characters DEP/,
(c) Then, without a space, insert the estimated off-block time.
EXAMPLE-

KSMF2215
ZZZZ0330

The same wording is used for both FAA and ICAO flight plan instructions.

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How long does it take for a contrail to hit the ground?
I'm not even sure if they end up falling to earth, or if they accumulate and form/join other clouds or whatnot, which is part of the reason I'm asking this question.
In contrails, heavier particles fall faster than the light ones, so as the contrail disperses it spreads vertically as well as horizontally.
How long does it take for a contrail to fall back to earth if at all?  If they do make it to the ground, is it then water vapor that touches down?

the material it is made up of remains there until it rains

Jet engines contrails are not different from cirrus clouds. Cirrus are among the few clouds that don't cause rain. Instead the ice or water particles dissipate when descending, due to reheating, without falling on the ground.

A contrail is a cirrus cloud composed from water vapor nucleating on soot in the engine exhaust and the contrail itself doesn't fall to the ground.  You will occasionally see cirrus uncinus "mare's tails" form from contrails, which are heavier ice particles in the contrail precipitating from the contrail.  These particles evaporate long before reaching the ground.

(image courtesy of Wikipedia, CC licensed)
The fate of the contrail cloud itself is death via entrainment.  Watch some over time as they distort from the winds aloft and then mix with the surrounding dry air and evaporate.
Once the contrail is gone and only vapor remains it moves with the air it resides in.  For synoptic scale flows, vertical motion of the atmosphere is on the scale of centimeters per second and as such until that vapor finds its way into subsiding air (e.g. a high pressure system, the dry conveyor belt of a midlatitude cyclone), it will tend to remain aloft.

The speed of evaporation is also a pretty good indicator of moisture levels at higher altitudes.  If they are gone quickly or do not form at all,  the surrounding air is relatively dry (and vv).

"Sublimation" might be more physically exact than "evaporation" as long as those are ice crystals.

The vast majority of the output from a jet engine is carbon dioxide (CO2) and water (H2O). The resulting excess of water vapour compared to the surrounding air can cause the water vapour to condense and then freeze, creating the visible contrails.
Carbon dioxide and water vapour are perfectly normal constituents of the atmosphere, and so do not "fall" to the ground in any meaningful sense. Water molecules in jet exhaust might eventually fall as rain somewhere, but the water cycle as a whole is not significantly affected by contrails.
There may be other molecules present in jet exhaust due to impurities in the fuel, but the amount of such impurities is almost certainly negligible.

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Do the pilots have to recalculate the balance when 6 passengers show up last minute in a 737?
Few years ago me and my mates forgot the checkin time and were late for flight. We were late for check-in counter closure (30 minutes before flight if i'm not wrong) but the staff allowed us to go on. We had no checked luggage. There were 6 of us so at least 400 additional kilograms to be carried. Do the pilot need to recalculate mass and balance or is it within the allowance?

If you were booked onto the flight, what makes you think your weight wasnt already accounted for?

IIRC, there is a document which lists all cargo and passenger carried on a flight. This document must be accurate and is updated for any last-minute changes. Therefore the check can be done when updating this document (which is done by dispatch anyway, not the pilots in the cockpit).

@Jamiec or the reverse of this question, do pilots have to recalculate these weight if 6 of us didn't make the flight?

Yes, that goes for the reverse as well. Airline manifests have to account for each person aboard. Depending on how the load schedule (envelope) is constructed, they don't necessarily worry about actual seat location so long as they know which zone you're sitting in.

Loadsheets have a section called 'last minute changes'. As the name implies, pilots can record last minute changes here. If the changes are minimal, there is no need to recalculate the mass and balance, and trim settings.
What constitutes 'minimal' depends on many things, principally limits set by the operator or manufacturer. I can't verify this but think 400kg would fall within these limits, unless the aircraft was already at its performance limits.

You are correct in that using the LMC section may simplify the calculations, but you would never depart with an incorrect passenger count on the loadsheet.

Chances are pretty good that the W&B was recalculated automatically as soon they decided to let you board. Pax manifests have to be accurate and just about everyone uses software tools to manage this. Once you have a pax & bag count, you plug the numbers into whatever zone they're in and boom done.

It depends. If the pilots had already completed the loadsheet, or received it from the handling company (more likely for a larger operator), then yes, they do have to recalculate, or request a new, updated loadsheet.
Otherwise, since no loadsheet has been issued, there is nothing to recalculate, for the pilots, but WHEN the loadsheet is calculated, it WILL include the latest numbers. Bottom line is: you will be included.
400 kg is enough to make a noticeable impact on performance (engine thrust setting) and take off speeds for a 737.
As another poster implies, there is often a last minute change (LMC) section for, well LMC's. There is also an upper limit of how large this LMC can be (ranging from 500-1500kgs for the 737-operators I have been with). An LMC usually takes about a minute.

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Is Electronic Flight Bag(EFB) any different from our day-to-day tablet?
Other than the fact that EFB must be installed with appropiate charts and other manuals, is there any difference between EFB and normal tablet? Can I use the same tablet I play Plant VS Zombie as EFB if I load appropiate charts?

There is no difference, most pilots use regular iPads.

The FAA (unsurprisingly) has definitions of different types of Electronic Flight Bag (EFB) systems, which you can find in AC 120-76C.  It's targeted at airlines, but the concepts are generally applicable.
They break them down into Class 1, Class 2, and Class 3 EFBs, and the answer is a little different for the different classes:

Class 1 EFB Hardware.
This is what most of us General Aviation Folks use: A portable computer or tablet considered "portable electronic devices" with no specific FAA approvals.
Per the FAA a Class 1 EFB can't be "mounted to the aircraft" or connected to the aircraft systems or a dedicated power supply (i.e. they can't be permanently wired into anything), but you can plug them in to an "existing aircraft power supply" (like the cigarette lighter port) for battery recharging.

This is what most of us GA folks are using - an iPad with Foreflight and Stratus is technically a "Class 1 EFB".
This is just a regular computer, so it can in fact be the same device you play Plants vs Zombies on (though if you're using it in an airline environment they've probably locked it down and restricted what you can do: Plants vs Zombies is probably not available in the cockpit of your Southwest flight).

Class 2 EFB Hardware.
Class 2 EFBs are essentially Class 1 EFBs that get mounted to the aircraft, but can be easily removed by the flight crew (for example a GPS or iPad in a panel-mounted cradle) and may connect to aircraft data systems via cables or wireless connections (for example Garmin's Flightstream system).
Class 2 EFBs have the same battery-charging provision as Class 1 EFBs, but can't be directly wired into aircraft power. As far as the FAA is concerned they're still "portable electronic devices".

This is what the more advanced bits of GA are using - An iPad with Garmin Pilot communicating with your GTN stack via flightstream to get its GPS position & transfer flight plans.
Again this can be the same device you play Plants vs Zombies on, but the operator may have locked it down to keep their crews from flying past their destination while playing with their laptops.

Class 3 EFB Hardware.
Class 3 EFBs are installed systems with FAA approvals (for type-certificated aircraft).
The chart data stored on e.g. a GTN650 or GMX200 with charts and plates loaded on it would qualify here, as would flight management systems on larger aircraft.

Generally you won't be playing Plants vs Zombies on Class 3 EFB hardware because the approvals for it wouldn't include that capability.
The exception here is the Experimental Aircraft community: Such aircraft may have a consumer tablet installed in the panel and wired into ship's power in such a way as to qualify for all practical purposes as a "Class 3 EFB", and it's possible you could play Plants vs Zombies on your installed iPad in such an aircraft.

@ymb1 I'm not sure how something like the FMS would be classified here, but it would seem to fit the description of "Class 3 EFB" - the iPads that have replaced chart binders on many airlines on the other hand would be Class 1 EFBs (or Class 2 if they connect to the onboard avionics for position & weather data)

@ymb1 Ohhh the one just aft of the captain's cupholder (where the clipboard for approach plates and such used to be) -- Yes, that's a Boeing-installed EFB available as an option on the 777, and since it's a permanently installed alteration to the aircraft it would be a Class 3 EFB :)

Our airline uses second and third generation iPads with CAA approved applications, cockpit mounts(holders) and chargers.
Basically, this combination of  iPad(tablet)+software+equipment is EFB.
If AppStore would't be locked you could install and play PvZ.
Heres you can find some material about EFB:
https://en.wikipedia.org/wiki/Electronic_flight_bag
http://www.skybrary.aero/index.php/Electronic_Flight_Bag
https://en.wikipedia.org/wiki/Cockpit_iPads


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How many controllers are there per frequency?
Imagine multiple controllers talking on the same frequency would be a nightmare for pilots and other controllers.
So in real life how many controllers are there for each frequency? If there are more than one, how do they split the work load?

There is one frequency per sector and there can be two controllers per sector, one working the scope / talking to aircraft and one assisting with flight strips and coordination with adjacent sectors. If the sector does not require a second controller to coordinate and assist with flight strips, there will only be one controller doing all tasks single-handedly.
In some cases, two sectors are combined and both frequencies are manned by the same controller, but this is only done in low-traffic times, where overlapping transmissions have a low probability.
A good and well-written source to understand how ATC sectors and split workload works is the AVWeb Series of Say Again? by Don Brown.
See this related question for more information:
What is the maximum number of planes a controller can control?

That very series (Say Again) actually mentions that the usual case is that there is no D-side :)

@falstro I reworded the answer. Most sectors in Germany don't have a D-side either, especially not the FIS specialists.

@falstro & SentryRaven, would one of you define D-side for the curious, non-pilots among us?

@FreeMan D-side, or Data-side, handles the flight strips, checking for potential conflicts before they get to the radar, and so on. The one handling the radar and the radio is called R-side (I think for radio-side)

I have heard were controllers of adjacent sectors would speak on the frequency (this is in the US). It usually happens when someone did not switch properly and they just ask them to switch over to their frequency, or when they want to stay in contact with someone who is out of the range of their frequency. Only happens rarely though!

And in addition, each control position (radar, associate, D-sdie, ground, tower, etc) can have up to two actual people: if on-the-job training is being conducted, both the trainee and the trainer (who is a certified controller) will be plugged in at the same time. The trainer has override capability so they can talk over their trainee if absolutely necessary.


text:
What are the circles/holes ahead of the wing of an MD-82?
In the picture below I noticed there are three circles or holes of some kind ahead of the wing, what are those?

(airliners.net)

I totally want I-SMEL in my logbook.

The three large circles indicated in the question are static port plates. These measure the static pressure of the surrounding air, which is used to measure airspeed and altitude.

Original Source
Thanks to a link from Jonathan Walters, here is a closeup of one:

The four smaller areas in a row along the centerline are the radar altimeter transmitters/receivers. The radar altimeter uses radio waves to determine the aircraft's altitude above the ground. This diagram for the A345 has them further aft, they're in similar configurations on other aircraft.

Original Source


text:
How many times does a pilot usually change local pressure while landing or departing?
The local air pressure (QFE, and therefore QNH as well) may change throughout the day. ATC will advise pilots of the new altimeter setting on a regular basis. How often do pilots truly update this altimeter setting?

what have you searched? why are you not satisfied with what you found?

Related, but IMO not exact duplicates: https://aviation.stackexchange.com/q/91330/54557, https://aviation.stackexchange.com/a/84232/54557. Note for any possible close-voters: I have personally observed a flight crew read back a new altimeter setting and fail to adjust the setting on their instruments. I feel like this is a question about technique rather than policy and deserves answers of its own.

QNH (or QFE) rarely changes fast enough that a pilot will need to adjust their altimeter during the departure and arrival phases unless they happen to be in the area when a new observation is announced (typically once an hour).
En route is different; assuming you’re below the Transition Altitude, you’ll typically get a new QNH from every ATC sector you pass through. If you’re not talking to ATC, you are still required to set your altimeter to the QNH of a station within 100 miles, so you’ll be changing at least once an hour and likely more often unless your aircraft is exceptionally slow.

A pilot typically does not make many changes to the pressure setting in flight. The pilot will set the altimeter to the local pressure setting before departure, and set it to the local pressure of the destination airfield before arrival. En route if the pilot is below transition altitude they will use the pressure setting as advised by ATC or using another source of information such as ATIS systems close to the route.
As a private pilot flying relatively short routes, say maximum of 3½ hours, in light aircraft the most I've ever had to change my altimeter setting in a flight is 5 times.

A pilot will need to set the most accurate pressure setting for the task at hand such as landing or departing at a field or despatching troops or stores. Once above a set altitude know as Transition Altitude a standard pressure setting is used for deconfliction purposes in the cruise however QNH can be used below while being sure it’s updated. The crew will typically change the QNH / QFE when notified by ATC or the ATIS when they are parked or taxiing, or when in a stable flight stage during the initial approach or during the climb. However they are unlikely to mess with the altimeter during the final approach or take off roll.


text:
What aircraft has this cockpit?
What is the aircraft shown in the cockpit photo below?
It was sent to me by someone who claims to be a pilot of this aircraft but I have my suspicions.

May I ask the reason for your suspicions?

It is an Airbus A320 family aircraft.
Based on the general layout and design, it looks like an Airbus aircraft (although that can be misleading sometimes). There are a few distinctive items to look at when distinguishing between different Airbus aircraft:
Engine instruments
The earlier A300 and A310 still used analog engine instruments, excluding these types since your picture shows the engine instruments on the upper central screen:

Thrust levers
The Airbus A340 and A380 have 4 engines and therefore 4 thrust levers, excluding these types since your picture shows only 2 thrust levers:

Screens
The newer A350 uses wider screens, excluding this type since your picture shows much smaller screens:

The A380 and the similar looking SSJ100 have taller screens instead:

Alternate Landing Gear Extension
This leaves us with the A320 and A330, which have very similar cockpit layouts. One easy way to distinguish them is the alternate landing gear extension system (the one for the A320 is mechanical and located on the rear pedestal, the one for the A330 is located just below the gear lever, marked in red below):

Also note the different landing gear indicator layout (marked in green in the pictures above), since the A330 accommodates for the extra center landing gear of the A340 (same family).
Conclusion
Therefore, the picture you show must be an A320 family aircraft. It is impossible to say which one (A318, A319, A320 or A321) based on that picture. Here is a comparison of the glareshield and pedestal:

And here for the overhead panel:

Image sources: A310, A340, A350, A380, SSJ100, A330 and A320.

Nice. Anything to distinguish this from an A-220 or the SSJ?

@RalphJ The SSJ can be quite confusing (hence my recent question). To me, the biggest visual difference is the screens (using portrait mode instead of square or landscape). The A220 looks a lot more different since it was designed by Bombardier (C series).

It matches very closely to this picture of an Airbus A320 cockpit.

Taken from Wikipedia at:
https://commons.wikimedia.org/wiki/File:Airbus_A320-214_Vueling_EC-HHA_cockpit_(5508849819).jpg


text:
Do pilots of modern high-end aircraft normally communicate their destination to ATC?
Do pilots of modern high-end aircraft ever verbally communicate their destination to ATC? My understanding is clearance delivery is done electronically and when listening to ATC I haven't heard any instance where the pilot stated the destination to ATC (either on takeoff or en-route).

You have to listen to Clearance Delivery not Tower or Center

In the usa, yes, the destination airport is transmitted verbally over the radio by many pilots at many airports.
As you say, at certain airports and for certain operators the IFR clearance may be issued non-verbally. In the USA there are two options: the Pre-Departure Clearance program (PDC) and the Controller-Pilot Data Link Communications — Departure Clearance program (CPDLC-DCL).
PDC clearances are issued by ATC "in the blind" without waiting for a request from the pilot,1 and so the departure airport is never confirmed; it is incumbent on the pilot to read their issued clearance and verify that the clearance limit is correct. CPDLC-DCL clearances require that the pilot be "logged on" to the CPDLC  system, but once they are connected to that system, the clearance is again issued automatically without a specific request by the pilot.2 When using CPDLC the pilot will confirm receipt of the clearance. In neither case will the destination airport be mentioned over a radio frequency.
However, if there is a problem with the clearance, or if either the ATC facility or the pilot does not have the equipment necessary to utilize PDC/CPDLC, the pilot will have to radio the Clearance Delivery controller and verbally request a clearance.
From the Aeronautical Information Manual 5–2–6h2, when calling on the radio to copy their IFR clearance, the pilot is expected to:

State the following information in the initial call‐up to the facility when no change has been made to the filed flight plan: Aircraft call sign, location, type operation (IFR) and the name of the airport (or fix) to which you expect clearance.

In my experience almost every pilot—Part 91, Part 135, and Part 121—will follow the above recommendation. They will verbally transmit their intended destination airport to the Clearance Delivery controller, despite the filed flight plan including that clearance limit already.

1 AC 90-117 Table 2-1
2 AC 90–117 2.10.3.2
Further reading:
AIM 5–2–2 Automated Pre-Departure Clearance Procedures
Advisory Circular 90-117 (thanks @ymb1)
ForeFlight: PDC FAQs
BoldMethod: Pre-Departure Clearance: What Is It?

PDC does require an action from the pilot. Either it is actively requested or - in case of the United States - it is sent after pilots log on to the ATC network (ie. make a "notification") before departure.

@busdriver: see my edited answer, which now specifies that it is correct for the USA only—I should have said that in the first place. PDC never requires a specific request from the pilot, and I clarified that CPDLC-DCL also does not require a specific request but does require the pilot to log on to the CPDLC system.

Can you clarify whether your comment that most pilots will verbally transmit their intended destination applies to those using PDC/CPDLC? I have been listening to KAUS "clearance delivery" on liveatc and it seems virtually no one is requesting clearance over that channel.

@757toga, I am referring to the AIM specifically, which is (as we all know) not regulatory. But tag:FAA would not apply and IMO tag:USA would be too broad—though I am open to persuasion on that point.

@flopper: when pilots call CD to copy a verbal clearance they will state the destination airport. If you look at the airport diagram for AUS you will see that both PDC and CPDLC are available, so few if any of the airlines will call for a verbal clearance. If you instead listen to EDC ground/clearance on 119.45 you will likely hear some clearances being requested and issued. Check FlightAware to see when there might be a departing flight (they will call for clearance ~30-40 min prior to the time shown).

@757toga: "again" is a rhetorical device emphasizing the similarities between PDC and CPDLC-DCL, which are separate systems; it does not imply that the same clearance is issued via both systems.

The flight plan contains the desired route and destination.  Ot is communicated prior to the first radio call with clearance delivery.

Communicate - yes ;
Verbally - mostly ;
Digitally - sometimes
As stated above, anything but a simple VFR-Flight will require a flightplan, which noch only states the destination and the route. This flightplan is mostly filed in written (or via computer) (though sometimes this can also be done via audio)
Next, the pilot will request a clearance, which states the destination again - this is normally done via voice-radio, though sometimes digitally transmissions is being used.
=> ATC is aware of your destination

Every flight that intends to fly in controlled airspace needs to make a flight plan in advance that includes destination and intended route. In case of airlines, the flight plan is submitted by the dispatch office prior to flight.
Before departing, the flight needs a clearance that is merely a confirmation of the flight plan. In theory the clearance could include changes in filed route but that is rarely case in these days as any conflicts are in practice handled by the airline. In countries where the flight plan is required to include local departure procedures those are sometimes altered by the requirements of the departure airport.
The destination and route is confirmed (an thus communicated) when pilots request a route clearance. At major airports the clearance is issued usually by datalink so no verbal communication is required and even if voice procedures are used, the ATC already knows the destination of the flight as it is included in the flight plan.

I disagree that a clearance is "merely a confirmation of the flight plan." The clearance is the clearance and the flight plan is nothing but a plan. Just filing a flight plan is not sufficient to fly IFR in controlled airspace; the flight plan means nothing, the clearance means everything. And at least in the USA, ATC-issued reroutes are far from rare.

Also a flight plan is not required for every flight in controlled airspace- consider a VFR flight.

-1 In Europe, if "modern high-end aircraft" are VFR then they don't need to file a flight plan to cross CAS (they do need a clearance).  Not sure about FAA-land but there's no location tag in the question.

"Every flight that intends to fly in controlled airspace needs to make a flight plan in advance"   HAH!  Tell that to my C-172.  I frequently take off without even knowing where I'm going, I can make it up along the way.

@DaveGremlin “Controlled Airspace” includes class E, which only requires a clearance if you’re IFR.

@StephenS   Oh yes, class E, I always forget about that, there's a bit near Belfast, and didn't Aberdeen get a wedge a few years back?  I've never been near class E so never been caught out. Mind, I don't need a clearance to cross a MATZ but I always 'request a penetration'. https://i1.wp.com/nats.aero/blog/wp-content/uploads/2017/05/UKAirspaceClassifications.jpg


text:
What would be the lowest possible cabin altitude (respectively, highest possible pressure on board) of an airliner in 1155 Pa exterior pressure?
How well does an airliner's pressurization work at extremely high altitudes (extremely low atmospheric pressure)? Does the system provide an absolute pressure differential, or is the differential a factor of the ambient pressure?
For example, consider an airliner in an environment where the atmospheric pressure is 1155 Pa (0.1675 psi). Such an environment may be found at an altitude of approximately 100,000 ft on Earth, or in the Hellas Basin on Mars. What cabin altitude could the airliner simulate?
When at 41,000 ft (pressure 2.6 psi) above the Earth's sea level an airliner simulates a cabin altitude of 8,000 ft (10.9 psi), which is 4.19 times the pressure of 2.6 psi at FL410. So if we took $0.1675 \times 4.19$ it would mean an airliner could provide an onboard pressure of 0.7 psi, the pressure around 68,000 ft MSL. Is it correct to assume that you have to multiply by 4.19 to get the result or did I miss something?

This is borderline off topic for me as you are asking about an impossible situation. An airliner cannot get to the altitudes where they would experience near vacuum.

Are you asking about structural integrity of the airframe or about the engine's capability to provide the pressurized air?

@GdD But it's an interesting thought experiment.

@Bianfable Only about providing pressurized air if it were possible (which it isn't but that doesn't matter).

I think you have a fundamental misunderstanding about how airliner pressurization works.

@GdD Possible. An answer could help in this matter.

@Giovanni I don't understand what you expect us to say about "providing pressurized air if it were possible (which it isn't but that doesn't matter)". If it's not possible, how can we write a meaningful answer? Such speculation is off-topic.

@Bianfable It's only about the pressure in the cabin. I'm asking on a B737 that is on Mars' surface, i.e. not flying, possibly driving. Alternatively you can think of a B737 flying slightly below 100K ft altitude above Earth but that's even less possible. The question is what cabin altitude/pressure could be generated when the exterior pressure is 1155 Pa / 0.1675 psi.

I think it's far more possible to get a Boeing 737 up to 100 thousand feet than get it to the surface of mars @Giovanni.

@GdD No, both is equally (im)possible, but it's far more possible that a B737 is standing on solid ground than flying through near-vacuum.

So you think it is more possible to transport an airliner through millions of miles of space then soft-land it on the surface of another planet that barely has a shred of an atmosphere than it would be to get it up to 100,000ft above our own planet?

@GdD and upvoter The plane would need to fly on its own at 100K ft which is impossible, but the how is completely irrelevant, my question is about the if. Theoretical questions should be allowed.

@Bianfable and others: the question seems to boil down to How does an airliner pressurization system work? What is its maximum altitude? How will performance degrade above its maximum altitude? These questions may or may not be duplicates of others on the site, and may or may not require splitting into separate posts, but they seem on-topic to aviation. +1.

@randomhead I appreciate your effort to make the question on-topic. I'm still not entirely convinced that there is a non-speculative answer to the question, but I retracted my close vote...

@Bianfable I had already deleted almost all references on Mars before randomhead's edit. But I'm thanking him due to the even better expression now.

@Giovanni - Which impossible things are you willing to ignore? If pressurized air comes from bleed air from the engines then the engines must be running. 737 engines won’t run in the Mars atmosphere.  And I‘m pretty sure they’d wouldn’t be able to run at 100,000 ft on Earth. Without them you get no pressurization.

It would have been better if users countered my arguments against their nonsensical protests rather than sticking to their downvotes and stubborness in that they're simply correct without dealing with most obvious things and the question itself.

@Jim That could have been part of an answer. But it's also impossible to run an engine at FL1000 even if the atmosphere was 100% oxygen.

@Giovanni - I think the answer cannot be given yet, because we don’t know the assumptions we can make.  The question needs to be clarified.

Sea level pressure in PSI is 14.7.  If you are in space and are holding sea level cabin the differential would be 14.7 - 0 (or very close to it) = 14.7 PSID.  The space shuttle must withstand a differential near this value

PSI differential (pounds per square inch) is relative, so the difference in psi is comparable as you suggested.  So you can do around 10.9 - 2.6 + .1675
or around 8.4675 psi or around 13,000 feet.  This is a bit better than 68,000 feet, which is above the Armstrong limit where full space suits must be worn.
But why not check out what the Virgin Galactic Spaceship 2, New Shephard, Dream Chaser, or Space Shuttle could do.
Any rapid decompression of an airliner cabin would be almost instantly fatal to unprotected passengers under those conditions$^1$. Forget about dropping oxygen masks, air pressure on Mars is way to low to get sufficient O2 into your body, even breathing pure oxygen, unless you have a pressurized suit.
Shuttle astronauts routinely worked in shirt sleeves throughout much of their missions.
$^1$ even if a 737 was capable of doing it

Metal bodied airliners are generally limited to about 8+ psi differential. The carbon 787 goes to 10 as do some high altitude corporate airplanes.  8.3 psi gives you an 8000 ft cabin at 41000 ft.


text:
What is the name of the format of route with the dots? Eg. DTW..LAYNE.DXO006 (...)
I found in our data a route formatted with dots instead of with spaces and DCTs. Example:
DTW..LAYNE.DXO006.BNNET.YQG341.DIRKS.J38.GRB/0052

What is the name of this format?
Second question: Sometimes instead of .. and . after the departure airports there is ./.—what does it mean? Example:
KIAH./.ABCD..BEREE.BEREE1.KDFW

Note that in your DTW example, DXO006 and YQG341 are not points in space but specified radials off of VORs. This is why they use single dots to connect to the fixes BNNET and DIRKS.

This is an ATC routing format, introduced long ago, with the IBM 9020 mainframe. The dots are element separators, used because spaces would signify a new field in the flight plan. Two dots separate like elements (ABCD..BEREE would be two points, J107..J148 would be two airways) and single dots separate unlike elements (BEREE.BEREE1 is a fix followed by a route [in this case a STAR with the fix name in it]).
Two dots do not necessarily mean "direct;" all they signify is a connection between two like elements. But it is true that when the two like elements are both points in space, rather than routes, the meaning is "direct to the next point in space."
The ./. construct is called a tailoring symbol, and is used to indicate previous routing which has been dropped (PANC./.DDY..MBW.RAMMS5.KDEN) because it is no longer needed (there may have been ten elements or more between PANC and DDY). In other words, once your flight passed ABCD, nothing between your departure point and ABCD was needed anymore.
You may also see, on a flight plan strip, three stars: PANC./.DDY..MBW***KDEN. This indicates additional routing which was not printed on the strip due to a lack of physical space. If you request a "full route" for the aircraft you can see the actual route instead of ***. (This is not the case for the tailoring symbol, which will not be expanded out on a full-route strip.)
Also, for an added bonus, the /0052 at the end of your route is the estimated time enroute (in hours and minutes) for an inactive flight plan, or your estimated time of arrival (in UTC) for an active flight plan.
There's some history to add here, for controllers, as well. I knew a gentleman by the name of Frank Cox who actually worked on the IBM9020 CHI (Computer-Human Interface) as a Radar Input SME. He told me the reason why the radar route key required spaces between elements (and routes were not allowed), while the AM (amendment button) format required dots between elements-
"I worked in DC with the radar team, in the R&D building, on the second floor. The D-Side team worked in the same building, same floor, two doors down the hall. We never talked to each other."

I thought . was for connected elements (like the fix to enter/exit an airway) and .. was for direct?

".." separates like elements (J123..J456, DIR..ECT) while "." separates dissimilar elements (J123.DIR, ECT.J456).

@StephenS  In case case of, say, 2 VORs, ABC..DEF, the .. happens to BE direct routing from the one to the next, but that isn't the definition of the .. there. Just happens to match.

@RalphJ Got it; thanks!

Thanks for the assist, randomhead!

Also, @ randomhead, strips also use the tailoring symbol for additional route that is suppressed. (see https://atcmemes.com/does-atc-read-remarks-section-flight-plans/ )

For the "J123..J345" style processing to work, there has to be an internal fix adapted at the airway junction, so this doesn't always work. Most of these fixes are adapted for stratum-specific airways (so, no "J148..V169" or "T280'..J151", etc). It all depends on local adaptation.


text:
For KPDX LOC 21 approach, how is the procedure turn performed when entering from the east?

On the Portland, Oregon Loc 21 approach....
Let's say I was east at CARBY (not shown) and traveling on a northwest heading to CREAK (about 280 or so). CREAK is on the approach plate and an IAF/IF.  I am at 6,000 MSL.
What happens at CREAK?  This might be nonsense/not even allowed as I was testing it on a flight simulator and don't know if a controller would ever the assignment.  In any case, I had myself (in the sim) traveling northwest to intercept CREAK at 6k...
What should I do at CREAK?  Lets assume that I have to do the full approach as the controller just said "Cleared for the approach" elsewhere and portland tower was closed?
Again, not sure if that could ever happen with this specific approach (as it is in a radar environment) and probably open 24/7.
Upon reaching CREAK, would I .... turn to a heading of 030 for a few miles to go out, then turn left to a heading of 344 for a bit, then turn left again to 164 in order to intercept the localized and continue back to CREAK and down?
On the approach plate, CREAK looks well to the southwest of the procedure turn barb (it said remain within 10nm)?
Would I instead make a right turn at CREAK and turn/maneuver to enter the final approach course?

AFAIK the position of the procedure turn barb relative to the IAF is not significant; the "Remain within 10NM" is. But I'm not a pilot.

Note that tower being open or closed has nothing to do with whether or not you must execute the course reversal, nor with whether or not you receive "cleared approach" or vectors to final. (Although if the TRACON was closed it is much more likely that the overlying Center would be unable or unwilling to provide vectors to final.)

The reason for a procedure turn is to provide a self contained, published means for a pilot to reverse course with minimal controller involvement.  If you are on a heading of 280 you are only 70 degrees off the final approach course and nicely set up for a modified left base leg, so there really isn't any reason to execute the full procedure turn.
Personally I don't see any reason to go all the way to CREAK either.  There is significant terrain in the area, and 18.7 miles is WAY out there... especially for a light piston single GA airplane.  By time you complete the procedure turn you would be almost half the distance of a cross country away from the airport!
If it were me I would ask for direct to COVDU.  An 11.3 DME modified base would avoid the highest terrain and give any category aircraft plenty of room to set up for the approach and get into landing configuration.  There would be a little more controller workload to help you get established, but really only a single vector 40+ degrees left as you approach COVDU would be needed to put you on a 30 degree or less intercept to final, and this would allow them to clear you for the straight in approach.
ADDENDUM:
If you are proceeding direct to the airport and they simply clear you for the approach with no other modifiers, (such as "cleared for the straight in"...) they do expect you to execute the procedure turn.  In that respect I haven't answered your question as to how you should do that, because it makes no sense to perform a course reversal - to perform a course reversal.  (and in the process driving 20 miles the other way, over mountains, in IMC.) I wouldn't accept it.
If, however, you have requested vectors and been informed you can expect that, then approaching COVDU you are told "N123X, turn left heading 230, maintain at or above three thousand five hundred until established on the localizer, cleared LOC/DME runway 21" then you are good to go.  No course reversal is needed, expected, or even practical to execute at that point.
I know the controllers are supposed to say "straight in" when there is no expectation to do the PT, but I honestly don't recall hearing it much, if ever.

"Vectors to COVDU" could work, because COVDU is greater than three miles from the final approach fix HUDUT. But you won't get a "base:" Where adequate radar coverage exists, radar facilities may clear an aircraft to any fix 3 NM or more prior to the FAF, along the final approach course, at an intercept angle not greater than 30 degrees 7110.65 4–8–1a5. This may less work for the controller than true vectors-to-final, but it's not guaranteed, especially if the controller said "cleared approach."

@randomhead, good feedback, thanks.  I made a few minor edits to my answer as a result, please let me know if you have anything else...

Looking at it again, this is a helpful answer in this specific case but doesn't actually answer OP's question, which is: If you are on the "I could conceivably do a straight-in" side of an instrument approach, and ATC says "cleared approach", should you execute a course reversal; and if so, how?

From previous discussions, and from looking at the .65 4–8–1e, I believe the answer to "do you have to" is: 1) the rules say you have to execute the course reversal unless ATC says "cleared straight-in," and 2) many controllers aren't aware of that and will clear you without saying "straight-in" even when that's what they expect.

@randomhead, please see my addendum and let me know what you think.  Thanks.

Two things: 1) you would need a clearance to the IAF CREAK, as a "cleared approach" when you were still direct the airport wouldn't be legal I'm pretty sure. That phraseology can be used when you're on an airway or routing that has you going over an IAF. 2) What if OP really does need to lose altitude—say they're in a C750 instead of a C172 and they'll cross CREAK at 10000 coming from the east. How should the course reversal be accomplished? (Really this is a question for OP's CFII, I would imagine.)

@757 I don't think anyone is confused about that part. If ATC provides radar vectors, whether 1) vectors to intercept final approach course or 2) vectors to intercept a non-IF/IAF fix along approach course—note that both kinds of vectors allow no more than a 30° intercept—then the PT is not authorized. The question is what happens if ATC issues a clearance "direct CREAK" (which is the IAF and has a depicted PT) without a vector to ensure a 30° intercept.

@757 fair point. Personally I read OP's question as referring to a situation where radar vectors are not provided, and Michael's answer as discussing (mostly) a situation where they are, which may be the more common situation but is not what was asked.

@randomhead, the altitude at CREAK is at or below, so if you are coming out of the flight levels there is a lot of altitude to lose before you get there.  (a PT is no substitute for a STAR...)  Also, the OP's question isn't quite as specific as you are making it, but I agree that your interpretation is more correct than mine based strictly on what is actually said.  However, if someone asks the best way to drive a nail with a crescent wrench I will always always tell them to use a hammer...


text:
Which individual airframe has carried the most passengers in its lifetime?
I'm guessing that the airframe will be one of the 747s that service the domestic Japanese market, making regular short hops full of passengers - but perhaps actual figures exist to confirm this.
See also: Which airliners have carried the most passengers? for a related question about passengers carried by an aircraft series.

I'm not sure what the difference is between this and the other question? Certainly an aircraft that carries the most passengers is an airliner, no?

Do you mean one aircraft, or one make and model of aircraft?

As the title says, and in distinction to the other question, this is about individual aircraft.

An answer would be possible if there are public databases linking airframe number and total passengers carried. It's unlikely such database exists, think of an airframe being used by successive operators for example: The owner of this database must be above the operators and registration countries, meaning IATA or manufacturer. But such information has little visible interest for them (in addition the number of boarding passengers is not significant, it can be x2 just by the presence of a stopover in the middle of the trip -- else the passengers*km value should be looked after)

I'm guessing it's probably have to be a Boeing 737 or A320.

Talking total body count over the lifetime of the aircraft, rather than max for a single flight, right?  If it's not one of the early model 747s, I'll bet it's a DC-3/C-47/Dakota... 70-80 years of short flights might outcount half that time with longer flights even at higher loading.

Probably the closest you could get is if a database exists that has the number of flights for each airframe. Then you could use an average load factor based on whatever airline statistics might be available, such as average load factor per type, per airline, etc. But there would probably be many airframes that are in the same general range, for example airframes that were built around the same time that flew with only one airline for their entire careers. With the statistical uncertainty you might at best maybe narrow it down to a particular type that flew with a particular airline.

Japan has very high demand for short distance flights.  At least according to Wikipedia, JAL had two 747-100BSR-SUD aircraft with 563 seats. Google Image Search shows numbers JA8170 and JA8187.  They first flew in 1986 and left JAL in 2006.  JA8170 was later operated by One-Two-Go until 2008 but JA8187 may have been operated until 2013 by Transaero.  It is likely JA8187 is the answer you are looking for.
Wikipedia suggests they were designed to fly 52,000 flights in 20 years.  Due to high weight and low fuel capacity, these planes only did shorter flights.  It is improbable that the seating capacity stayed the same for the entire life of the planes.
It seems unlikely that records of the passengers on all those flights can be found, but we can estimate.  If you assume 50% load factor and 3 flights/day for 20 years, you get 6 million passengers per air frame.

While Emirates announced a 644 seat A380 configuration "it will use on shorter, high-density routes" I doubt that actually existed; their Dubai hub has no short, high-density routes.  A380s have fewer seats than the 747-100BSR-SUD did and would rarely fly more than twice per day.


text:
Why does Fairbanks, AK have a terminal area chart?
It's a relatively uncluttered airspace. Why have a TAC?
FAI Terminal Area Chart

Arguably, Louisville, KY has at least the same complexity, and since it's UPS's hub it's far more active. Plus, it's a legit controlled airspace, instead of a terminal radar area.
SDF as shown on the St. Louis sectional

Are there historical reasons, reasons which aren't immediately obvious, or is it just some kind of cynical inflation of importance?

Fairbanks is just as much "legit controlled airspace" as Louisville is. Class E, by definition, is controlled airspace.

Also note that the ICAO code for Fairbanks is not KFAI... which is yet another example of why pilots operating in the US should be in the habit of giving the three- or four-character FAA Location ID and NOT the four-letter ICAO code.

I don't have an answer, but two differences are that PAFA has significant terrain close to the airport, and there's also a lot of military activity around it (at least, that's what some of the comments on the TAC imply). Neither of those things are an issue for KSDF. I used to fly out of KLOU, and I don't think anyone considers it "complex" airspace. The PAFA area looks a lot more complex to me, in fact.

@Pondlife I agree; KSDF is a pretty simple class C that I wouldn’t think twice about flying through. PAFA is part of a triple-primary TRSA with six non-towered airports in their surface areas, plus significant terrain and nearby SUA; I would appreciate the added detail of a TAC if I had to fly there VFR.

Aside from the nearby military fields, PAFA has commercial aviation and a huge amount of GA traffic.  In addition to the 'main' runway, there is a shorter paved runway as well as a gravel ski strip and a water runway.  I count 6 visual reference points around the area. Much more variability than that organized stream of UPS traffic at SDF.

@randomhead thanks for the edits, they make the question better. Definitely didn't know that about the ICAO code. We'll agree to disagree that Class E is a controlled airspace in the sense of VFR pilots having to establish comms with ATC. There's plenty of Class E in the US, but FAI is the only one I know of which gets a TAC.

@KennSebesta It looks like the chart shows that FAI is class D, meaning that a VFR pilot would indeed need to establish comms before entering. I’m not sure if that’s what you meant, though.

@KennSebesta TRSA is a special kind of class E. And “controlled” means something very different to VFR and IFR pilots.

@StephenS as an instrument pilot, I agree completely. But a TAC isn't particularly helpful for me when flying instrument, it's primarily a tool I use for VFR flight. I'm not saying FAI's TRSA shouldn't have a TAC, but it's the outlier in that there are no other TRSA which warrant a TAC, and the only two Class C in the nation which have a TAC are in Alaska and all of Puerto Rico.

@Pondlife, whelp, maybe that right there is why there's a TAC. I had missed the Class D hidden in the contours of the TSRA and Class E. It's a lot easier to see on the TAC than the sectional!

@KennSebesta AFAIK, every TRSA has at least one class D, and most don’t get a TAC. PAFA is weird because it has 3 D’s. That’s probably part of why it does.


text:
Do US military aircraft have tail numbers beginning with "N"?
Military aircraft usually display a serial number along with other insignia on the tail or body of the aircraft, as described here.  However military serial numbers are not the same as FAA tail numbers on civilian US aircraft, which begin with the letter "N".
Do military aircraft also have an "N" number, or do US military aircraft simply not have an "N" number?

The 'N' numbers you're referring to are FAA registration numbers. The FARs (Federal Aviation Regulations) specifically mention registration as not being required for military aircraft:
14 CFR 47.3

(b) No person may operate an aircraft that is eligible for registration under 49 U.S.C. 44101-44104, unless the aircraft—
(1) Has been registered by its owner;
(2) Is carrying aboard the temporary authorization required by §47.31(c); or
(3) Is an aircraft of the Armed Forces

The FAA issues these registrations in accordance with its responsibilities under the Chicago Convention on International Civil Aviation, which required (in Article 20) that:

Every aircraft engaged in international air navigation shall bear its appropriate nationality and registration marks.

As per the above-cited 14 CFR 47.3, though, the U.S. specifically requires that all eligible aircraft have registrations unless it's either a military aircraft or it has temporary authorization under 14 CFR 47.31(c).

You cite both FAA regs and the history of those regulations from a 1947 aviation convention: +1 sir!

The FAA shares more history about N numbers here.

The military uses buno (beuno?) numbers to identify specific aircraft.  An aircrafts side number may change over its history, but the buno number remains constant.

BuNo = bureau number, a unique serial number used by the navy, assigned sequentially.  army and air force use a similar system, 6 or 7 digits long where the first two digits is the year of acquisition, followed by 4 or 5 digits unique to each year grouping.  actually putting this number on the aircraft seems to follow several different standards.

As @reirab explained, "N" registration numbers are generally used for civilian aircraft.  However, there are some notable exceptions.
The de Havilland DHC-7 (aka "Dash-7", variously nomenclatured O-5A, EO-5B/C, or RC-7B) is used by the United States Army as its Airborne Reconnassaince-Low manned aerial imagery intelligence platform.

Image credit: Alan Radecki / Wikimedia Foundation
Another de Havilland, this one a DHC-6, is used by the Air Force Academy's parachuting team:

Image credit: Ian Tate / Flickr
Dover AFB's 436 Force Support Squadron employs several Cessnas at their Aero Club, used for flight training.  One of them made the news when it made an emergency landing onto a local highway.

Image credit: Adrian R. Rowan / Dover AFB
These are just a start.  Getting creative with search queries, you can also find hundreds of other aircraft listed in the FAA registration database.
Virtually all of these are very special-purpose aircraft, with no munitions or other armament (aside from chaff/flare as in the case of the Dash 7).

And although not technically military (yet), it is common for developmental aircraft to be given civilian registration numbers during flight testing phases prior to final delivery.  This prototype KC-46A, painted mostly in military-style "livery", has registration number N461FT.

Image credit: Ken Fielding / Wikimedia

Interesting that the KC-46A needed an FAA registration prior to the US military taking ownership.

@steampowered Since it's technically not "an aircraft of the armed forces" until they actually sell it to the Air Force, it would run afoul of 14 CFR 47.3(b) if they didn't register it (or at least apply for the registration) before flight testing.

Good point with this answer, @erich. The FARs just say that the military isn't required to get a registration number; they don't say that they can't get one.

And then there are probably aircraft that are owned by DoD but aren't part of the armed forces. VIP transports and such for non-military senior staff.


text:
What is the technical name for the “time boxes” on an instrument approach plate?
Some instrument approach plates include a list of groundspeeds and times from the FAF to the MAP. What is the real name for these time boxes?

https://www.reddit.com/r/flying/comments/8ienph/instrument_rating_donezo_checkride_writeup/dyrb9qb/ Related question, eh? :)

Per the FAA Aeronautical Chart User’s Guide for Terminal Procedure Publications, in the revision effective 29 March 2018 on pages 30 and 31, it is a Time/Distance Table.

Time/Distance Table
When applicable, a Time/Distance Table is provided below the airport sketch. The table provides the distance and time
  that is required from the final approach fix to the missed approach point for select groundspeeds.


text:
What made 800 feet and later 1,000 feet attractive as the standard traffic pattern altitude?
The value of a commonly understood traffic pattern altitude is obvious, but what is the history behind TPA of eight hundred feet in particular? Why not 700 or 900?
Was the later move to 1,000 AGL because of easy math only, or were there other reasons?

It's worth mentioning that 1,000' AGL might be popular for smaller aircraft, but at many airports 1,500' AGL is used for twins and turbine aircraft. Still I'm sure the answer will be fascinating if anyone has some research.

Possible factors: Noise and view angle. Higher = less noise, lower = better view on the field. 800 ft may have been a good compromise at the time. With traffic and noise increase it could have been necessary to climb a bit.

Possible duplicate of Why do some airports have a non standard traffic pattern altitude?

The traffic pattern altitude (and the pattern turn direction) is set by the airport owner in coordination with the FAA. Refer to section 8.
Airport traffic patterns are often 1000 ft. AGL today. In recent past, the typical altitude above ground level was 800 ft. Flying Magazine, in a September 1958 article states:

Under VFR conditions proper entry into the zone is sadly neglected. Before you enter the control zone you should be at the Pattern Altitude which is more or less standard rule at every airport in the country--800 to 1,000 feet for light aircraft, 1,200 to 1,500 for heavy or fast aircraft. This provides you with altitude, yet gives plenty of room to make your turns. Letting down in traffic makes you vulnerable and blind, at the same time increasing the odds of hitting someone you will never see"

Experts and non-experts seem to agree an altitude increase would be beneficial:

Better noise abatement near the airport environment
Increasing tower heights
1000 is easier to remember than 800

Fun facts:

Tangier island/KTGI airport elevation is 6 ft mean sea level. The traffic pattern altitude is 605 ft.
Truckee/KTRK is 5901 ft. MSL with an 1100 ft. TPA.
Sedona/KSEZ is 4830 ft. MSL. The TPA is 1173 ft.

Pilots flying into Sedona must be precise, haha!

TGI has a restricted area above it at 700ft. The other two just even out the TPA to 7,000MSL and 6,000MSL, respectively. Not really a big deal

Maybe not a big deal but definitely one of those worthless aviation facts I'll never be able to forget.


text:
What are the differences between radar flight following and traffic advisories?
In typical usage, the terms seem to be used interchangeably. However, aircraft must be transponder- or encoder-equipped for traffic advisories to be possible, for example.
What information does each provide to pilots that the other does not?

You can get both by asking ATC for either one. I understand traffic advisories to be one of the benefits of flight following. See this AOPA article on the subject.

See also the Pilot/Controller Glossary entries on RADAR ADVISORY, FLIGHT FOLLOWING, and TRAFFIC ADVISORIES.

Services provided by ATC depend on the airspace class. When only advisory service is provided, ATC doesn't provide vectors or assign flight levels, only traffic information. This may vary by countries. Typically this is the F airspace (not used in the US).

Your second sentence is not correct. Traffic advisories may be called both to and about primary-only targets, provided there is sufficient primary radar coverage.

To my ear as a controller in the United States, "flight following" implies a desire to remain in contact with ATC for the purpose of receiving traffic advisories on a cross-country flight to a specific destination airport. Any other term ("traffic advisories" or "radar advisories" or similar) implies not that, e.g. traffic advisories in a more limited area, such as a Class C/B airspace transition or air work in a practice area or a sightseeing flight. If this distinction was codified and explicitly taught to pilots and controllers it would reduce the amount of questions I have to ask when someone calls up asking for VFR services.
But not every controller feels strongly about this, and the FAA's Pilot/Controller Glossary entry for FLIGHT FOLLOWING simply points to TRAFFIC ADVISORIES.

Depends on the ANSP (Air Navigation Service Provider) to what each term means to them. In most ANSPs they mean exactly the same thing or their individual regulations only have one of these terms/procedures available.
A traffic advisory technically doesn't always require a transponder especially if it is of a snapshot of traffic. The pilot requesting the traffic advisory gives position and a one time traffic picture is provided to the pilot. This is mainly relevant in areas where there is not Secondary Surveillance coverage and/or no surveillance coverage at all.
However Flight Following does require being able to be identified for continual coverage. Some ANSPs also provide additional reporting services with those receiving flight following like SAR services and Hazard Alerting services.
Some ANSPs only provide these services at the discretion of the controller based on their own perceived workload.
Check the local regulations for the ANSP your flying in to get exactly what you will be provided


text:
Advantages in using a flight sim to prep for a private license?
I'm starting to save up to get my pilots license and I was thinking I might be able to do some amount of prep work by using a flight simulator.  That being said, I realize there must be some huge limitations to what I can actually learn, on my own, on a flight sim.
So, out of curiosity, are there good things to try practicing on my own in a flight sim?  There's got to be a few basic things that would make it worth my time...  Otherwise I'll just go back to flying around aimlessly like I usually do :).

I bought a Saitek rudder/yoke/quadrant setup and FSX a few years ago, and I've found the hardest thing to do is pattern work.  Having to control your head in-game to look out the window and get an idea of your location is very difficult and not something you'd even have to think about in the real thing.  Other than that, make sure you turn off "easy mode" in the sim.  P-factor and a lot of weather is turned off by default in FSX, for example.

@Pondlife - Aw, the title of the other one was a bit misleading for me.  Yeah, it looks like the other thread has this covered.  Thanks for linking me.

Just a small additional suggestion:  Spending a couple of hours with a flight instructor now (even while you are saving up the money to take "real" lessons) on the simulator can show you what you can be practicing and help keep you from learning some bad habits.

I'd advise against "flying around aimlessly".
Even if it is a simple, routine flight between two nearby airports, fly it fully, and try to fly it as professionally as possible (can you keep your heading to within +/- 3 degrees? can you keep your altitude spot-on?)
Another good exercise is to do all your navigation planning in detail (each heading for a certain number of minutes), then try to take off, and using nothing but the compass and stopwatch, find out how close you get.  (and when you end up off-course, figure out where you went wrong!)

+1 that was something I was really looking for, very practical and objective. Just need a good simulator rig now


text:
What control issues did the X-1 have to overcome to achieve supersonic flight?
In Chuck Yeager's autobiography, he went into a little bit of detail as to why the X-1 was able to break the sound barrier safely where as the P-51D he flew during WWII could not have safely broken the sound barrier.  He mentioned it had to do with the controls... Something about flow separation, as I recall, and the elevator not working as a result in most aircraft before the X-1.
I was wondering if someone could explain this though?  What advances where made during X-1 development that made it stable at Mach 1?

The control problems are caused by a shift of the aerodynamic forces. In subsonic flight, they are mostly created in the forward part of the wing (the lift increase with angle of attack works at the quarter chord point of a wing, regardless of sweep), while in supersonic flow they work equally over the full chord. The center of lift in pure supersonic flow is at mid chord, and in reality the aerodynamic center shifts slowly back when the aircraft accelerates through Mach 1 and more of the surface is exposed to supersonic flow.
Since the c.g. position is mostly fixed (Concorde pumped fuel between tanks to shift the c.g.), this shift must be compensated with elevator deflection. The elevator must move trailing edge up, which creates a break in the airfoil contour, which in turn creates a heavy shockwave at high subsonic and supersonic flight speed. This shock causes flow separation and can lead to elevator reversal. Only when the fixed part of the horizontal tail can be moved, too, or you have a full-flying tail (the whole stabilizer is moved, not only the rear part of it) to create the needed lift change without a contour break, the aircraft can be trimmed for both subsonic and supersonic speed.
The benefit of the X-1 was a stabilizer with variable incidence, which the P-51 lacked. Sweep would have helped, too, but was not really necessary.

I posted a question about chord particularly to help me understand the answer to this one...if you have a moment...  And while I'm at it, what is "incidence" and how do you make it variable versus...fixed, I 'd guess?

@JayCarr for the variable incidence of the horizontal tail look at horizontal stabilators. In these tails the whole horizontal stabilizer can rotate, not just the elevator. In the EMB-145 the elevator trim adjusts the angle of the stabilator rather than moving a trim tab on the control surface.

@casey That does make some sense, but I'm not sure what you mean by "incidence".  It sounds like horizontal tail did something embarrassing it would rather not talk about to my ears...

@JayCarr http://en.m.wikipedia.org/wiki/Angle_of_incidence

@casey Ah...just to double check my work:  the angle of incidence is the angle between the chord line of the wing and the longitudinal axis of the craft body?

@Jay Carr: Yes, this is correct. Please see this link, it might be better than a wordy description: http://knowtothis.blogspot.de/2009/12/adjustable-stabilizer.html#.U3ut114YQlU

"Only when the fixed part of the horizontal tail can be moved, too, or you have a full-flying tail... [can] the aircraft... be trimmed for both subsonic and supersonic speed."  Or if you have very large elevators.

The phenomenon you are describing is called "Mach tuck." As Peter described, the location of the lift forces changes, which can be more than the elevator can compensate for.
There is also another factor at work. This image shows what is happening on a wing or tail surface near supersonic speeds. At the higher speeds, a flow separation is shown. This means that the flow is no longer "sticking" to the surface, instead creating turbulence in that area. This flow separation occurs at the trailing edge, exactly where the control surfaces tend to be. This means that instead of deflecting into smooth flow, they enter turbulence. This can cause buffeting in the controls, and makes the control surfaces much less effective.
The solution to this problem was to move the entire tail surface instead of just a trailing edge portion. Since this surface now acts as both the horizontal stabilizer and the elevator, it is called a "stabilator." You will notice this feature on most supersonic fighter jets.

So, basically you end up compensating for decreased flow over the back of the rear vertical stabilizer by simply moving the whole thing?  Is that right?

I always forget if the "horizontal" or "vertical" refers to the angle of the surface or the axis being stabalized...  Sorry, got that backwards.

Seems to me like an easier solution would be to make the tail a flat plate instead of airfoil-shaped.


text:
Does EASA (or other regional/national aviation safety authority) have a confidential "close-call" reporting system?
Not being a pilot, learned about the ASRS from this site. Have any aviation safety authorities in other countries attempted to emulate the ASRS and to what degree was it successful? After all it was introduced in 1976, which is quite a while ago.
I'm mostly interested in European airspace, although examples from other countries/regions are welcome.

The UK has CHIRP

@Simon - nice to know, thanks, are there any cross-country comparative impact assessments?

I don't know much about the ASRS, so but I think this is a similar program... It's obviously not Europe, but Australia has the REPCON scheme for confidentially reporting all sorts of safety matters. The ATSB do a bit of investigating, seeking a response from the airline/whatever organisation is involved, and then publish the responses to a couple in CASA's Flight Safety Australia magazine.

Is it a success? Do pilots trust the system?


text:
What is differential braking?
How is differential braking different from regular braking? How do you accomplish differential braking and why would you need to use it?

Aircraft with toe brakes have the brake pedals at the top of the rudder pedals.  You press the left one with top of your foot and it applies the left brake(s).  Press the right one to apply the right brake(s).  Normally you press them at the same time and with the same force to keep the airplane from veering to one side (imagine just locking up the brakes on one side of the airplane).

Differential braking is when you press one brake pedal harder than the other.  It is used as an additional form of directional control when:

You have no other forms of steering (either because the steering has failed or there is no nose-wheel steering)
The rudder/nose-wheel steering is not effective enough (because you are going too slow or the wind is too strong).

You want to be careful when doing this, though because you can over do it and create more directional control problems than you originally had.  If you use differential braking during the takeoff roll, it will increase the amount of runway that you use since you are applying the brakes (even though it is only on one side, it will keep you from accelerating as fast).

The takeoff roll is a good point. The technique I was taught for managing yawing tendencies in castering nosewheel types is to actually point off-centerline during the first part of the roll.

It's worth noting that while they're usually toe brakes (at the top of the rudder pedals) some planes have heel brakes.

Some airplanes don't even have the brakes on the foot pedals.  The Liberty XL-2 for example has finger brakes.  A bit of a challenge for transitioning pilots...  :-)

Also, differential braking is used routinely in light airplanes for parking (tight turns often required).

Simply put, differential braking means you can apply different brake pressure for each brake.  In a car you have one pedal that applies equal braking to all of your wheels.  In many airplanes you have two brake systems and you control the left side brakes independently from the right side -- this is differential braking.
To make use of differential braking, you need two brake pedals, these are typically actuated by applying toe pressure to the rudder pedals (known as toe brakes).  You press the right toe brake and the right main gear wheels have brake pressure applied -- likewise for the left toe brake.
You use this to aid in turning the aircraft, as in many light airplanes the nose wheel is free castering, you cannot control it.  In larger airplanes you have a tiller to steer the nose wheel, but differential braking can still be used to make tighter turns.

In "some" airplanes you have two independent systems.  Other airplanes have hand brakes, etc. that apply both brakes at the same time and make differential braking impossible.

I don't have a citation for this, but the classically famous Mikoyan-Gurevich MiG-15 jet fighter was fitted with differential braking, which operated via the rudder pedals in conjunction with a lever on the joystick.  As I recall, the instructions were:  to brake in a straight line, remove feet from both rudder pedals and squeeze the brake handle.  To use brakes for turning, deflect one rudder pedal and squeeze the handle.
Typical USSR equipment.  Astonishing performance considering the technology available, but if you don't know exactly what you're doing you can kill yourself just trying to get off the ramp.


text:
At what bank angle does load factor's effect on performance increase?
I had this question on my Part 107 exam today. After some thought, I opted for a) 15 degrees, since that is the minimum bank angle at which the load begins to increase. Was I right?

Load factors have a greater effect on both flight performance and loads on a fixed-wing aircraft as the bank angle increases beyond approximately?
a) 15 degrees
b) 30 degrees
c) 45 degrees

I think this is an ill-posed question, it increases for any non-zero bank angle. So the question is what is considered 'enough' of an increase.

What a stupid question.  The exam question, I mean.  God bless the FAA.  I mean seriously.  They could have said something like "increase 'significantly' by which we mean greater than 5%", or whatever else they wanted to say, but as written, it's just dumb, dumb, dumb.

Seriously I am an actual pilot and have no idea what the right answer should be.  Would tend to pick (b) though, assuming the question is asking about a noticeable increase.  Though really the graph suggests the bank angle has to get up to 35 degrees or so before there's any increase that's likely to be noticeable to a pilot.  Which seems more or less in line w/ my actual experience.  So -- ???

Note that the load factor's effect on performance could largely be associated with an increase in stall speed, and the increase in stall speed is equal to the square root of the increase in load factor.  My intuition that you'd need a bank angle of significantly more than 30 degrees to notice any significant increase in the stall speed associated w' steady-state flight (constant vertical speed).  Even though you may perceive some slight increase in G-load at a slightly shallower bank angle.  All in all a very subjective, and therefore lousy, question.

From the FAA Remote Pilot Study Guide chapter 4 comes the following graph:

From this graph I suspect they want you to notice that the slope really starts to pick up at around 30 degrees.
Edit:
There have been several comments on the quality of the graph here. But note that this is their graph not mine. They make the graph and the test so I’d expect them to be at least internally consistent. However, the text accompanying the graph in the same section says,

Figure 4-2 reveals an important fact about turns—the load factor increases at a terrific rate after a bank has reached 45° or 50°.

So it’s very unclear what answer they want you to pick.  But it’s probably not 15.

Interesting that the load factor looks like less than 1 at 0° of bank on that graph.

So the FAA cannot even plot an inverted cosine function properly? Sad!

Yep, I take no responsibility for their choice of graphic….

Should be approx 1.15 at 30 degrees -- but that's not what graph shows --!!

Actually, load factor (G's) required to maintain altitude increases as soon as you start to bank, but not linearly.
The cosine of the bank angle must give sufficient vertical lift.
At 0 degrees, this represents:  1 G vertical lift/cos bank angle = 1.000 G load factor
At 15 degrees:  1.035 G
At 30 degrees:  1.15 G
At 45 degrees:  1.41 G
So, don't be surprised if the answer is c.  I would pick a. as well.